This invention concerns a drawing frame for sheath made of plastic material such as shape-memory polyethylene, with high elastic deformation.
This drawing frame can be used for instance on a sheathing machine and in particular a machine for making silos, with bales of plants, fodder or other.
This type of machine such as that described notably in the document U.S. Pat. No. 5,220,772 for round bales or EP-0 789 993 for parallelepipedic bales, comprises generally an appropriate polygonal frame, associated with a main frame whose size is such that it enables the passage of the fodder bale. This frame comprises extenders consistingxe2x80x94of cantilever supports on which the plastic sheath is stored andxe2x80x94of actuators moving said supports radially in order to increase the perimeter of said sheath sufficiently to be able to insert the bales inside said sheath. The sheath is pulled down around said bales as they are produced, thereby forming a kind of sausage.
In view of the radial arrangement of the extenders, the machines of this type are particularly cumbersome and, due to the presence of an immovable polygonal frame, they are not suitable for bales of different gauges.
According to the invention, the sheath is stored on supports mounted on throated arms, whereas said supports are arranged and/or guided with respect to a fixed main frame in order to form a polygonal mouth piece and whereby one of these supports is mobile, subject to displacement means that cause the perimeter of the sheath to expand at said mouthpiece, whereas said displacement means consist of actuators arranged in a straight position on each mobile support and, some of them, on the main frame, whatever the shape of said mouth piece.
According to a preferred embodiment of the invention, the main frame takes the form of a horizontal beam comprising, on the one hand, arranged symmetrically with respect to the vertical plane of the polygon delineated by the sheathxe2x80x94fixed supports integral with said beam and,xe2x80x94two lateral structures, articulated on said horizontal beam, close to the fixed supports, and on which structures the mobile support(s) is(are) guided and, on the other hand, actuators forming, around the mouthpiece, a closed frame on said beam, arranged in a straight position on one another, starting from said beam and on the mobile support(s).
Still according to the invention, in the case of a drawing frame for round bales, each lateral structure has for instance the shape of a dihedron, consisting of two beams forming slide rails that delineate an angle of approx. 120xc2x0 in the case of a mouthpiece and of a hexagonal frame:xe2x80x94a first beam articulated at one of its ends on the horizontal beam of the main frame close to each fixed support,xe2x80x94a second beam mounted to run at one of its ends on the first beam, comprising a mobile support situated on the bisecting plane of the angle delineated by said first and second beams,xe2x80x94a slide at the end of the second beam comprising another mobile support.
Still according to a preferred embodiment of the invention, the hexagonal frame consistsxe2x80x94of two lateral dihedral structures and of two actuators in each dihedron,xe2x80x94with the addition of an actuator extending between the ends of two lateral structures, at their upper section, interposed between the slides arranged at the ends of the second beams of said structures andxe2x80x94of the horizontal beam of the main frame that serves as a sixth side.
In the case of square bales, the drawing frame according to the invention comprises lateral structures in the form of single beams articulated on either side of the fixed lower supports, on the horizontal beam of the main frame, whereas each beam serves as a guide for a slide that is fitted with a sheath support, whereby said slides are interconnected by a horizontal actuator and are connected to the main frame each by an actuator and the frame consists therefore: of said horizontal beam, of the lateral beams and of the horizontal upper actuator.
Still according to the invention, the lateral structures of the drawing frame are interconnected by a kind of rudder bar that maintains each of them in such a position that they are constantly symmetrical with respect to one another and with respect to the middle vertical plane going through the longitudinal axis of the drawing frame, i.e. the insertion axis of the bales; said rudder bar has the shape of a transversal axle guided on the main frame of the drawing frame and fitted at its lateral ends with arms parallel to one another and whose end of each is integral, using an appropriate link, with the corresponding lateral structure.
According to another embodiment of the invention, the supports of the plastic sheath are mounted on throated arms in order to place the stored sheath on the plane of the actuators and of the slide rails, whereby each arm is integral with a slide or with the main frame and whereby each support comprises a fixed pallet in the form of a cylindrical section.
The invention also concerns a sheathing machine for bales of plants, that comprises a drawing frame such as described previously and a hydraulic control station of the various actuators that are power supplied from a stand-alone plant or from a plant arranged on a farming vehicle such as a tractor.
This drawing frame may for instance be used on a stand-alone sheathing machine, i.e. fitted with its own pusher as described in the document CA-2 111 546, as well as on a simpler machine for which the bales are pushed directly by the loading vehicle.
Still according to the invention, this machine comprises a main frame mounted on transport wheels and this main frame also comprises, on the silo side, i.e. of the sheathed bales, girders fitted with pad-shaped members and/or suitable wheels according to the nature of the soil, and possibly fitted with spades that maintain the machine in position and prevent it from reversing as the bales are inserted into the mouthpiece of the sheath.
According to another arrangement of the invention, the anchoring points of the handling actuators are multiple, so that the size of the mouthpiece and of the frame can be adapted easily to the gauge of the bales to be sheathed.